Cassius in Julius Caesar by William Shakespeare instigates the plot to kill Caesar. The accepted perception of Cassius follows Antony's belief that he is a noble Roman senator and general and not dangerous to Caesar.
In Act 1, Scene ii, Cassius sees Brutus outside the Colosseum. Cassius's intention is to draw Brutus into the conspiracy to assassinate Caesar. Brutus asks Cassius to explain his intentions. The reader learns of Cassius's character from what his tone and the words that he chooses.
To begin, Cassius threatens suicide if Caesar becomes the emperor of Rome. From past events, Cassius has grown to despise Caesar. His hatred for Caesar clouds his judgment and reasoning. To him, Caesar is weak as he describes how he had to save Caesar from drowning. Further, his anger stems from his feelings of equality with Caesar. He and Caesar have grown up the same.
And this man
Is now become a god, and Cassius is
A wretched creature, and must bend his body
If Caesar carelessly but nod on him.
Caesar's good fortune enrages Cassius's jealousy. His fury rises as he describes other times when Caesar demonstrated his human faults: he groans; he asks the gods for help; he shakes with a fever; and he has fits.
Ay, and that tongue of his that bade the Romans
Mark him and write his speeches in their books, Alas, it cried, “Give me some drink, Titinius, Like a sick girl.
Finally, he admits his actual inner turmoil when he tells Brutus that it is ridiculous that Caesar should have all the glory to himself. Aye, there is the rub. Cassius believes that he too has given much to Rome, so why he is not favored as is Caesar.
Cassius will not be satisfied until Caesar is lying dead on the floor of the Roman senate. Cassius's oratory does its work and gives Brutus many things of which to ruminate.